‘Read Econmic News Together’ Series

A probe to Jupiter has arrived successfully

IT WAS exactly rocket science. In the early hours of Tuesday morning, cruising at a speed of around a quarter of a million kilometres an hour, some 868m km from Earth, and with Jupiter, the solar system’s biggest planet, looming in its cameras, a small space-going robot called Juno began a delicate task. This was to slam on the brakes and slow itself enough to allow it to be captured by Jupiter’s gravity.

Orbital insertions are difficult manoeuvres at the best of times. But Juno was beyond any human help. It had about half an hour to complete its job and, even at the speed of light, messages from the probe back to its masters on Earth would take longer than that to arrive. If anything went wrong it would therefore have to cope on its own.

In the end, everything went flawlessly. Back on Earth, watching humans breathed a sigh of relief: “To know we can go to bed tonight not worrying about what is going to happen tomorrow is just awesome,” said Diane Brown of NASA’s Jet Propulsion Laboratory, which built Juno.

Over the next couple of years, in a series of looping orbits designed to minimise its exposure to Jupiter’s fierce radiation belts, the probe will poke and prod the giant planet. Jupiter, along with Saturn, is one of the solar system’s two “gas giants”—big planets with extremely thick atmospheres made mostly of hydrogen and helium. It is more than twice as massive as all the other planets in the solar system put together. But it has had only one other probe, Galileo, which arrived in 1995, dedicated to its study.

Juno will examine Jupiter’s atmosphere, characterise its magnetic fields and try to determine whether there is a rocky core below the deep, roiling atmosphere, or whether the hydrogen and helium simply get denser and denser the further down you go. NASA also hopes that understanding Jupiter—especially how and where it formed—will shed light on how the early solar system evolved. That will help astronomers understand planetary systems revolving around stars other than the sun. The study of such exoplanets has thrown up hundreds of examples of “hot Jupiters”, giant orbs that orbit close to their parent stars. Every model of planetary formation says these could not have formed in situ. The assumption, therefore, is that they formed elsewhere before wandering closer to their parents. If Jupiter shows signs of having done something similar, that could help the understanding of millions of other gas giants elsewhere in the galaxy, too.